package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.MyCacheUtil;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    private static final ExecutorService CACHED_REBUILD_EXECUTORS = Executors.newFixedThreadPool(10);
    @Resource
    private MyCacheUtil myCacheUtil;
    @Override
    public Result queryServiceById(Long id) {
        //缓存穿透
//        Shop shop = queryShopPassThrough(id);
        //缓存穿透 工具类是实现
        //function位置也可以写成: this::getById
//        myCacheUtil.cachePassThroughByNull(RedisConstants.CACHE_SHOP_KEY,
//                id,Shop.class,id2->getById(id2),RedisConstants.CACHE_SHOP_TTL,TimeUnit.MINUTES);

        //缓存击穿  互斥锁
//        Shop shop = queryShopWithMutex(id);
        //缓存击穿 逻辑过期时间
//        Shop shop = queryShopWithLogicalExpire(id);
        //缓存击穿 逻辑过期时间工具类实现
        Shop shop = myCacheUtil.cachePierceByLogicalExpire(RedisConstants.CACHE_SHOP_KEY,id,Shop.class,
                                        RedisConstants.CACHE_SHOP_TTL,TimeUnit.MINUTES, this::getById);
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }


    /**
     * 获取锁
     * @param key
     * @return
     */
    private boolean tryLock(String key){
        Boolean aBoolean = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(aBoolean);
    }


    /**
     * 删除锁
     * @param key
     */
    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }

    @Override
    @Transactional
    public Result updateDB(Shop shop) {
        Long id = shop.getId();
        if(id == null){
            return Result.fail("店铺id不能为空");
        }
        //1. 更新数据库
        updateById(shop);
        //2. 删除缓存
        stringRedisTemplate.delete(RedisConstants.CACHE_SHOP_KEY+shop.getId());
        return Result.ok();
    }

    /**
     * 查询附近商户
     * @param typeId 店铺类型id（美食、玩乐）
     * @param current 当前页数
     * @param x 经纬度坐标
     * @param y 经纬度坐标Å
     * @return
     */
    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1. 判断是否需要根据坐标查询
        if(x == null || y == null){
        // 根据类型分页查询
        Page<Shop> page = query()
                .eq("type_id", typeId)
                .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
        // 返回数据
        return Result.ok(page.getRecords());
        }
        //2. 计算分页参数
        int from = (current - 1)*SystemConstants.MAX_PAGE_SIZE;
        int end = current * SystemConstants.MAX_PAGE_SIZE;
        //3. 查询redis、按照距离排序、分页。结果:shopId、distance
        String key = RedisConstants.SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end));
        //4. 解析出id
        if(results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> content = results.getContent();
        if(content.size() <= from){
            return Result.ok(Collections.emptyList());
        }
        //4.1 截取from-end部分
        List<Long> ids = new ArrayList<>(content.size());
        Map<String,Distance> distanceMap = new HashMap<>(content.size());
        content.stream().skip(from).forEach(result->{
            //4.2 获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //4.3 获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        //5. 根据id查询shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("order by field(id," + idStr + ")").list();
        //6. 返回
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);
    }

    /**
     * 查询店铺 解决缓存穿透
     * @param id
     * @return
     */
    public Shop queryShopPassThrough(Long id) {
        //1. 从redis中查询商铺缓存
        String shop = stringRedisTemplate.opsForValue().get(RedisConstants.CACHE_SHOP_KEY+id);
        //2.判断是否存在
        if(StrUtil.isNotBlank(shop)){
            //3.存在，直接返回
            return JSONUtil.toBean(shop,Shop.class);
        }
        if(shop != null){
            return null;
        }
        //4.不存在，根据id查询数据库
        Shop shopFrDB = getById(id);
        //5.数据库中不存在，返回错误信息
        if(shopFrDB == null){
            //解决缓存穿透
            //5.1 将空值存入redis中
            stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id, "", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
            //5.2 返回错误信息
            return null;
        }
        //6.数据库中存在，写入redis
        //6.1 缓存更新策略 添加过期时间
        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id, JSONUtil.toJsonStr(shopFrDB), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return JSONUtil.toBean(shop,Shop.class);
    }

    /**
     * 基于互斥锁解决缓存击穿问题
     * @param id
     * @return
     */
    public Shop queryShopWithMutex(Long id) {
        //1. 从redis中查询商铺缓存
        String shop = stringRedisTemplate.opsForValue().get(RedisConstants.CACHE_SHOP_KEY+id);
        //2.判断是否存在
        if(StrUtil.isNotBlank(shop)){
            //3.存在，直接返回
            return JSONUtil.toBean(shop,Shop.class);
        }
        if(shop != null){
            return null;
        }
        //4. 实现缓存重建
        //4.1 获取互斥锁
        boolean isGetLock = tryLock(RedisConstants.LOCK_SHOP_KEY + id);
        try {
            //4.2 判断是否获取成功
            if(!isGetLock){
                //4.3 失败则休眠并重试
                Thread.sleep(50);
                return queryShopWithMutex(id);//获取锁成功再次检测缓存是否存在，如果存在则无需重建缓存
            }

           Thread.sleep(200);//模拟缓存重建
            //4.4 成功，根据id查询数据库
            Shop shopFrDB = getById(id);
            //5.数据库中不存在，返回错误信息
            if(shopFrDB == null){
                //解决缓存穿透
                //5.1 将空值存入redis中
                stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id, "", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
                //5.2 返回错误信息
                return null;
            }
            //6.数据库中存在，写入redis
            //6.1 缓存更新策略 添加过期时间
            stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id, JSONUtil.toJsonStr(shopFrDB), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //7. 释放互斥锁
            unLock(RedisConstants.LOCK_SHOP_KEY+id);
        }
        //8.返回
        return JSONUtil.toBean(shop,Shop.class);
    }


    /**
     * 将高频访问key加入缓存
     * @param id
     * @param expireSeconds
     */
    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
        //1. 查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //2. 封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3. 写入redis
        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }

    /**
     * 基于逻辑过期解决缓存击穿问题
     * @param id
     * @return
     */
    public Shop queryShopWithLogicalExpire(Long id) {
        //1. 从redis中查询商铺缓存
        String shop = stringRedisTemplate.opsForValue().get(RedisConstants.CACHE_SHOP_KEY+id);
        //2.判断缓存是否命中
        if(StrUtil.isBlank(shop)){
            //3. 未命中返回空
            return null;
        }
        //4.命中，将json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shop, RedisData.class);
        Shop shopMsg = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断缓存是否过期
        //5.1 未过期，直接返回
        if(expireTime.isAfter(LocalDateTime.now())){
            return shopMsg;
        }
        //5.2 过期，需要缓存重建
        //6. 缓存重建
        //6.1 尝试获取互斥锁
        boolean isGLock = tryLock(RedisConstants.LOCK_SHOP_KEY+id);
        //6.2 判断是否获取锁
        if(isGLock){
            //6.3 获取锁，开启独立线程，实现缓存重建
            CACHED_REBUILD_EXECUTORS.submit(()->{
                try {
                    this.saveShop2Redis(id,20l);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    //释放锁
                    unLock(RedisConstants.LOCK_SHOP_KEY+id);
                }
            });
        }
        //6.4 未获取锁，返回过期商户信息
        return shopMsg;
    }


}
